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Pterosaur springs dampen the debate over their evolution

Artistic rendering of card-tailed pterosaur springs and everything. The discovery of new filaments on two species of pterosaur suggests that the extinct flying reptiles had complex coats of "springs" and fuzz, "the authors said of a new study. The presence of these obvious pterosaur springs can indicate that the ancestors of both the pterosaurs and their cousins, dinosaurs, had similar coverings &#821 1; but that is not the only hypothesis. Like dinosaurs, the pterosaurs are arosaurs. This group of reptiles, which also includes crocodiles, probably arose during the late period (more than 250 million years ago) and dominated the Mesozoan era that followed. Archosaurs overflowed all the way up to about 66 million years ago and the endangered mass eradication, which only happened to a dinosaur line (birds) and some crocodiles. Genuine springs with complex, branched structures have been found on several theropods – one of the most important branches of the dinosaur family and the line containing birds. Less complex filaments, similar to fuzz or down, have been found on some non-theropod dinosaurs. For decades, paleontologists have also found filaments on well-preserved pterosaur fossils. These filaments, known as pycnofibers, have been simple structures – imagine a hollow unbreakable tube – as illustrators usually make a fur-like cover when they recreate the animals. A more complex story takes shape [19659005] Today, researchers report that they found four different types of plover fibers on two copies of Card-tailed pterosaurs from the Middle-Late Jurassic of China over 160 million years ago. Type…

Artistic rendering of card-tailed pterosaur springs and everything.

The discovery of new filaments on two species of pterosaur suggests that the extinct flying reptiles had complex coats of “springs” and fuzz, “the authors said of a new study. The presence of these obvious pterosaur springs can indicate that the ancestors of both the pterosaurs and their cousins, dinosaurs, had similar coverings &#821

1; but that is not the only hypothesis.

Like dinosaurs, the pterosaurs are arosaurs. This group of reptiles, which also includes crocodiles, probably arose during the late period (more than 250 million years ago) and dominated the Mesozoan era that followed. Archosaurs overflowed all the way up to about 66 million years ago and the endangered mass eradication, which only happened to a dinosaur line (birds) and some crocodiles.

Genuine springs with complex, branched structures have been found on several theropods – one of the most important branches of the dinosaur family and the line containing birds. Less complex filaments, similar to fuzz or down, have been found on some non-theropod dinosaurs.

For decades, paleontologists have also found filaments on well-preserved pterosaur fossils. These filaments, known as pycnofibers, have been simple structures – imagine a hollow unbreakable tube – as illustrators usually make a fur-like cover when they recreate the animals.

A more complex story takes shape [19659005] Today, researchers report that they found four different types of plover fibers on two copies of Card-tailed pterosaurs from the Middle-Late Jurassic of China over 160 million years ago.

Type 1, as described in The new study is the simple hollow pycnibiber seen on other pterosaur fossils. This type covers most of the body of each test body, reminiscent of the mammalian underflow, the authors say, which indicates that it may have played a role in thermoregulation.

The other three types, however, appear to be branched structures and occur only in specific areas. Type 4, for example, superficially similar to a tree branch (see (n) in the image below) occurs only on the wing membrane.

Fossilized pterosaurpycnibras found on individuals include Type 1, a single hollow tube (s) and three more complex types that the authors say have branch structures similar to true springs (h, k, n). (Credit: Baoyu Jiang, Michael Benton et al. / Nature Ecology & Evolution)

Types 2 and 3 (h and k above) appear to have different branch structures and were found only on small parts of the head, neck and limbs of a test.

Further analysis of all four types of pigeon fibers revealed that they have a chemical signature similar to human hair and the feathers of living birds.

Preserved within the pike fibers, say the authors, are melanosomes: cellular structures that give clues to the animal’s pigmentation in life. Fossilized melanosomes have recently been used to reconstruct iridescent dinosaur springs, but the pterosaurs were apparently not really flamboyant. Based on their melanosomes, the flying reptiles would have been mostly brown.

Convergent Controversy

The presence of apparently branched pycnofibers on fossils revives a general debate about feathers in Archosauria. Scientists and armchairs palaeontologists have long argued when real feathers have evolved and in what lines.

(Most researchers believe that the first feathers probably arose for isolation and display, to signal a person’s fitness to a potential mate. Only a lot later along the evolutionary road they were coordinated by some species for use in flight.) [19659005] A school of thought holds that true branched feathers evolved among the therapists, but not all therapists sported them. There is no evidence that T. rex and other iconic megapredators had feathers. This hypothesis suggests that some unbranched feathers or other threaded structures found on pterosauria and non-theropod dinosaurs were examples of converging development when unrelated species that occupy the same ecological niche develop similar properties.

According to this hypothesis, pterosaurs pycnofibres originated independently from dinosaur springs.

However, the new analysis of the pinofibres of the two Chinese pterosaurs can be seen as evidence of another hypothesis: that the present archosaur fathers of both dinosaurs and pterosaurs had feathers of some kind and passed the property down to both groups.

The authors of today’s research contained a comparative analysis of thread and feather development in pterosauria and other archosaurs, especially dinosaurs. (Credit: Baoyu Jiang, Michael Benton et al. / Natural Ecology and Evolution)

Today’s paper is not the first time scientists have declared that they have essentially found pterosaur feathers. Pycnofibers on another Chinese pterosaur, Pterorhynchus wellnhoferi was described as branching and homologous with feathers, but subsequent analysis by other palaeontologists questioned these conclusions. The previous document, like today’s study, is not slam dunk in part because analysis of the pycnofibers is as much art as science and open to interpretation.

The new research occurs in Nature Ecology & Evolution .



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